R134a Liquid Level in a Receiver-Drier During Charge Determination, Steady State, and Transient Conditions

There currently exists a large variation in receiver-drier design in automotive TXV air conditioning applications. This is partly due to a lack of understanding of the impact of the receiver on A/C system operation. In order to study this, a see-through receiver has been built and used to study the liquid levels and refrigerant flow inside the receiver-drier in a TXV system. A charge determination test was conducted with the see-through receiver to determine the liquid level before, during, and after the charge plateau. Tests were conducted at steady state conditions to determine the liquid levels at various vehicle conditions. Transient tests were also conducted to study liquid levels during system changes, and run-dry conditions were determined. The TXV position was also tracked to correlate TXV reactions to system conditions, to assist In developing the theory of R/D operation in a TXV system. This work has lead to a better understanding on the role of the receiver-drier in a TXV system, and could lead to a more systematic approach to receiver sizing.